Diesel engine fuels



United. States Patent DIESEL ENGINE FUELS James L. Lauer, Philadelphia,and Archibald P. S tuart,

Media, Pa., assignors to Sun Oil Company, Philadelphia, Pa., acorporation of New Jersey No Drawing. Filed Nov. 22, 1957, Ser. No.698,051

2 Claims. (Cl. 44-57) This invention relates to the use of organicamines together with carbonyls of chromium, molybdenum and tungsten, andto the use of metal ammino carbonyls produced by the reaction of theabove metal hexacarbonyls with amines, to improve the ignitioncharacteristics of diesel fuels.

In diesel engine operation, air is compressed to a suiticiently highpressure and temperature in the engine cornbustion chambers to ignite apetroleum hydrocarbon fuel which is injected into the combustion chamberafter compression of the air. An important characteristic of thehydrocarbon diesel fuel is the ignition delay period, i.e., the timeinterval between injection of the hydrocarbon fuel into the combustionchamber and its ignition therein. The ignition delay characteristic of adiesel fuel is conveniently expressed in terms of a cetane number whichis the percentage of n-cetane in a mixture of n-cetane and alpha-methylnaphthalene having the same ignition delay characteristics as the dieselfuel. Fuels having too great an ignition delay period, i.e., too low acetane number, cause excessive engine knocking and rough running, anddecrease the life and efiiciency of the engine.

' .It .has previously been observed that the presence of chromiumhexacarbonyl in a diesel fuel reduces the ignition delay period, i.e.,raises the cetane number of that fuel to a small degree. It is alsoknown that organic amines, in general, increase the ignition delayperiod, i.e., lower the cetane number of a dieselfuel. It has now beenfound that by using both a hexacarbonyl of chromium, molybdenum ortungsten and an organic amine, or by using the reaction product of sucha hexacarbonyl with an organic amine, as diesel fuel. additives,

the cetane number of the resulting fuel composition is improvedsubstantially over that observed with the hexacarbonyl as the soleadditive. One or more of the metal hexacarbonyls together with one ormore of the amines can be used or, alternatively, one .or more of thecorresponding metal amminocarbonyls can be employed in accordance withthe practice of the invention.

The amines used according to the invention, either together with themetal hexacarbonyls, or to prepare the metal ammino carbonyls byreaction with the metal hexacarbonyl are preferably tertiary amines, butprimary and secondary amines can also be used. Amines having at leastone hydrocarbon substituent of from 1 to 12 carbon atoms are within thescope of the invention. The hydrocarbon substituents attached to thenitrogen atom of the amine can be alkyl, aralkyl, aryl or alkarylradicals. Suitable alkyl radicals, for example, are those having lessthan about 7 carbon atoms per group, while suitable aryl radicalsinclude both mononuclear and dinuclear aromatic radicals having lessthan 13 carbon atoms. Aralkyl and/or alkaryl radicals having less thanabout 9 carbon atoms per group are preferred. Specific examples ofpreferred tertiary amines are triphenylamine, trimethylamine,triethylamine, tripropylamine, tributylamine, trihexylamine,methyldiethylamine, N,N-dimethylaniline,

Eatented May 2,1961

r 2 ethyldiphenylamine, and-the like.

The metal ammino carbonyls used in this invention have the followinggeneral formula: 7

)y(X)z.

where M is chromium, molybdenum or tungsten,

an organic amine as defined hereinabove, and y and z are whole numbersof from 1 to 5, and the sum of which is 6. These compounds are suitablyformed by reacting f the metal hexacarbonyl with a suitable amine atelevated temperature, e.g., 200 F. or higher. r 1

Generally metal ammino carbonyls having the general formula M(CO X orM(CIO) X are most readily formed during the reaction between the metalhexacarbonyl. and the amine. However, other metal ammino carbonyls canbe formed within the scope of the general formula set forth above. -Allof the amino carbonyls of chromium, molybdenum and tungsten can be usedin the present invention. Specific examples of suitable metal amminocarbonyls are Cr(CO) C H N) )4[( s s)a l2. )4( e 5 z)s,' Mo(CO)(0-toluidine) Mo(CO) (o-toluicline) and the like. a t

Diesel fuels which are used in the practice of the invention arehydrocarbon mixtures normally derived from petroleum and boiling in therange of about 350 F. to 700 F. at atmospheric pressure. These dieselfuels can contain, in addition, additives-such as pour point dewpressants, viscosity improvers, and the like which are known in the art.Y e l The novel ignition improvers of the present invention, ordecomposition products thereof, normally do not deposit in enginecombustion chambers in sufficient amount; t to cause significant enginewear or other problems. How, ever, if desired, scavenging agents can be,used to sup-. press deposition of. the ignition improvers or decomposition products thereof. Halogenated hydrocarbonssuch as ethylenedibromide, ethylene dichloride, carbon tetrachloride, diandtrichloropentanes,. diandtrichlorobu, tanes, tetrachlorobutanes,dichlorobenzene, tetrachlorof benzene, benzotrichloride,benzotribromide, beuzotrihexacarbonyls and the amines, or alternativelythe me'tal' ammino carbonyls, are added to the hydrocarbon diesel.

fuel prior to the injection .of the fuel into the combustionl chambersof a'die'sel engine. .The metal hexacarbqnylsi and the amines, as wellas the corresponding metal ammino carbonyls, are sufiiciently soluble indiesel me hydrocarbons so that suitable amounts ,of these additiveg, asdescribed hereinafter, can readily be. dissolved in-thediesel fuel.Although not usually required, mutual sqlg. v

vents and/or dispersing agents can be used if desired to"v improve thestability tions.

When both metal hexacarbonyls and aminesai'elemq, ,7 ployed, therelativeproportions of the. amine coinpon t; to the metal hexacarbonyl component'canwarygbe Other amines can be used include diethylamine,diphenylamine, N-ethyly of the. novel diesel fuel compoSi-; V

6:1 and 1:1 on a molar basis. Mole ratios for the amine component to themetal hexacarbonyl component offrom 4:1 to 2:1 are distinctly preferred.Generally, thetotal amount of the metal hexacarbonyl and amine, or ofthe metal ammino carbonyl'by itself, is suitably equal to form about0.005 to about 5.0% by weight of the resulting fuel composition. Amountsin the range of from about 0.01% to about 2.0% are preferred.

In a second practice of the invention, applicable only where one or moremetal ammino hexacarbonyl is emploved, the novel diesel fuel ignitionimprover is introduced into the engine combustion chambers in admixturewith the air which is charged thereto. In this embodiment of theinvention, the metal ammino carbonyl ignition improvers are admixed withthe diesel hydrocarbon fuel inside the engine combustion chambers afterinjection of the hydrocarbon fuel therein.

Chromium, molybdenum and tungsten ammino carbonyls have sufiicientlyhigh vapor pressure at normal conditions so that by contacting the aircharged to the engine with the metal ammino carbonyl, suflicientvolatilized metal ammino carbonyl is carried into the engine combustionchambers to effect a reduction in the ignition delay period of thediesel hydrocarbon fuel. Thus in this second practice of the inventionthe engine intake air is contacted with the metal ammino carbonyl priorto admission of the air to the engine combustion chambers. The metalammino carbonyls are normally solid, and this contact can convenientlybe effected by packing the intake air filter with the solid ignitionimprover in powder form. Other means known in the art for introducingthe metal ammino carbonyl in admixture with the air can be used.

Alternatively, in this second practice of the invention, suitableamounts of solid chromium, molybdenum and/ or tungsten ammino carbonylcan be directly introduced into the engine via the air intake manifold.These ignition improvers in powder form are sucked into the manifoldtogether with the engine air and introduced into the engine combustionchambers dispersed in the air. In the combustion chambers, the metalammino carbonyls are vaporized before injection and combustion of thefuel. Any suitable means known in the art can be employed for supplyingthe novel ignition improvers of this invention to the engine air intakemanifold. For

example, a container holding powdered metal ammino carbonyl can beconnected as by a tube to the engine intake manifold. During engineoperation, the powdered ignition improvers are aspirated into the intakemanifold by reason of the vacuum therein.

' In order to illustrate a specific embodiment of the invention,o-toluidine and molybdenum hexacarbonyl were reacted together at about250 F. in the ratio of about 5 mols of o-toluidine to about 1 mole ofmolybdenum hexacarbonyl. The reaction product, comprising molybdenumammino carbonyls represented mainly by the formulas M(CO) (o-toluidine)and M0(CO) (o-toluidine) was added to a commercially available kerosenediesel fuel having an atmospheric boiling range of from about 400 F. toabout 600 F. in an amount equal to about 1.5% by weight of the resultingfuel composition. The diesel fuel containing the molybdenum amminocarbonyl had a cetane number greater by 2.0 numbers than the same fuelwithout the additive of the invention.

Similar beneficial results were obtained when a physical admixture ofthe metal hexacarbonyl together with the amine was employed inaccordance with the invention. To illustrate the latter embodiment, aphysical admixture of o-toluidine and molybdenum hexacarbonyl wasprepared in the proportions of about 2:1 parts by Weight, respectively.These proportions are equivalent to a mole ratio of o-toluidine tomolybdenum hexacarbonyl of about 5:1, in the resultant physicaladmixture. This admixture was added to a commercially available kerosenediesel fuel in an amount equal to about 1.5% by 4 1 weight of theresulting fuel composition, the o-toluidine representing about 1.0% byweight, and the molybdenum hexacarbonyl representing about 0.5% byweight, of the final fuel. The kerosene diesel fuel so employed had anatmospheric boiling range of from about 400" F. to about 600 F. and,b'eforethe addition of the ignition improvers, had a cetane number ofabout 49.2. The same diesel fuel, after the addition of the physicaladmixture of o-toluidine and molybdenum hexacarbonyl as above describedhad a cetane number of about 53.4, or about 4.2 cetane numbers higherthan the base fuel, this latter value representing an improvement ofover 8.5% over the base fuel.

In order to demonstrate the synergistic beneficial effect of thephysical admixture of the amine with the metal hexacarbonyl over andabove that exhibited by the individual components separately, thefollowing tests were performed. A sample of the commercially availablekerosene diesel fuel used in the preceding example, having a cetanenumber of 49.2, was divided into two portions. To one portion was addedabout 1.0% by weight of o-toluidine and to the other 0.5 by weight ofmolybdenum hexacarbonyl. The individual concentrations of the additivesin the latter samples were the same as the individual concentrations ofthose additives when used together in the preceding example, wherein aphysical admixture of o-toluidine and molybdenum hexacarbonyl wasemployed in the same base fuel, As was to be expected in view of priorknowledge, the cetane number of the diesel fuel containing theo-toluidine alone was lowered by 2.6 numbers, while the cetane number ofthe fuel containing the molybdenum hexacarbonyl alone was raised by only2.0 numbers. Nevertheless, as was shown in the preceding example, whenthe o-toluidine and molybdenum hexacarbonyl were employed in the sameamounts, but together in the same fuel, the cetane num ber of that fuelwas raised by 42 numbers. This observed increase represents animprovement of 110% over and above the effect of the molybdenumhexacarbonyl alone. Thus it can readily be seen that an unexpectedbeneficial result is obtained when the two additives are used incombination.

When other embodiments of the invention are practiced, as hereindescribed, substantially equivalent results are obtained.

This application is a continuation-in-part of our application, SerialNumber 516,052, filed June 16, 1955, and

now abandoned.

The invention claimed is:

.1. A fuel composition consisting essentially of a petroleum hydrocarbondiesel fuel and from 0.005% to 5.0% by weight of additive materialconsisting of molybdenum hexacarbonyl and a primary alkaryl amine havingless than 9 carbon atoms, wherein the molar ratio of said amine tomolybdenum hexacarbonyl is in the range of from 6:1 to 1:1.

2. A fuel composition according to claim 1 wherein said amine istoluidine.

References Cited in the file of this patent UNITED STATES PATENTS1,779,061 Danner et a1 Oct. 31, 1930 1,940,096 Mueller-Cunradi Dec. 19,1933 2,164,151 Crandall et al June 27, 1939 2,602,049 Smith et al. July1, 1952 2,860,167 Brown Nov. 11, 1958 OTHER REFERENCES ChromiumHexacarbonyl I, The Preparation and Stability of Chromium Hexacarbonyl,by Cumming et al,. Jour. of Applied Physics (Soc. of Chem, Ind, London),vol. 2, part 2, November 1952, pp. 624-632.

Chromium Hexacarbonyl II, Chromium Hexacarbonyl as a Fuel Additive, byCumming et al., Journal of Applied Chem. (Soc. of Chem. Ind., London),vol. 5, part I, pp. 39-52, June 22, 1954

1. A FUEL COMPOSITION CONSISTING ESSENTIALLY OF A PETROLEUM HYDROCARBONDIESEL FUEL AND FROM 0.005% TO 5.0% BY WEIGHT OF ADDITIVE MATERIALCONSISTING OF MOLYBDENUM HEXACARBONYL AND A PRIMARY ALKARYL AMINE HAVINGLESS THAN 9 CARBON ATOMS, WHEREIN THE MOLAR RATIO OF SAID AMINE TOMOLYBDENUM HEXACARBONYL IS IN THE RANGE OF FROM 6:1 TO 1:1.